1. Field of the Invention
The present invention relates to a vehicle travel safety device.
Priority is claimed on Japanese Patent Application No. 2006-095296, filed Mar. 30, 2006, the content of which is incorporated herein by reference.
2. Description of Related Art
There is conventionally known a navigation device in which node data including for example of the locations and shapes of roads are stored in advance in a data storage portion to serve as a database. During travel of a vehicle, the navigation device for example detects the travel locus based on the turning angle measured by a gyroscope and travel time calculated by a predetermined calculation process, compares the shape of the road in the node data with the shape of the travel locus, and corrects the database in the case of there existing a portion in which the shapes differ (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2001-108450).
In the navigation device according to one example of the prior art mentioned above, during the execution of route guidance by the navigation device when the vehicle is traveling, the shape of a road in the node data and the shape of the travel locus are constantly compared. When the shape of the road in the node data and the shape of the travel locus differ, the device corrects the database appropriately. However, in the case of a travel locus in which the detected error relatively increases depending on the driving state of the driver, the correction processing of the database will be performed with excessive frequency. As a result, the problem arise in which the computation amount required for the correction processing surges.
The present invention was achieved in view of the above circumstances and has as its object to provide a vehicle travel safety device that is capable of improving the recognition accuracy of road shapes while preventing an extreme increase in the computation amount required for correction of road data.